(NOTE: This article is aimed at more technical users and goes into more detail than most people will need. If you’re simply looking to have your iPhone or iPad fixed, please see “Get Your iPhone and iPad Charging Problems Fixed” instead.)
Unofficial and Fake Cables- How They Can Damage iPhones and iPads
This article is intended to provide a brief overview of a very common cause of Tristar IC (charging chip) problems and failure- specifically the use of unofficial or fake cables, and the reasons they are a problem.
Although your average Apple user isn’t aware of it, the official Lightning cable isn’t just an overpriced USB cable. The connector includes several chips, including one that filters the current from the charger to remove and block various electrical fluctuations that can damage the device, and another chip that sets up the charging process in a safe manner via a password-protected “handshake”.
(Cables and peripherals from other manufacturers that have a genuine official “Made for iPhone/iPad/iPod” (MFi) endorsement from Apple contain the same chips and can be considered as safe as Apple’s own.)
Low-cost, non-certified cables (along with blatant fakes and those with a bogus MFi certificate) don’t contain those proprietary ICs and may well flood the device with current it isn’t prepared for, or fail to protect it from spikes and fluctuations from the charger itself. Now, to be sure, these cables will usually appear to work at first. However, as soon as there’s a voltage or current fluctuation, there’s a good chance the device will end up with serious motherboard damage or- at worst- completely dead.
The Background on Officially-Certified Cables
As mentioned above, all officially MFi (“Made for iPhone/iPad/iPod”) certified cables from third party manufacturers include the same chips as the official Apple ones, and provide the same protection for the device. Such companies sign up for the MFi scheme, and in exchange get a pre-manufactured connector containing the genuine chips.
There are a number of versions to suit the peripheral being manufactured, but Apple generally sells them for $4 or thereabouts. The third party makes the rest of the peripheral themselves (typically with their own name on it alongside the MFi certificate). This means that the Lightning connector itself contains Apple parts and is made to their specifications. (You can tell a fake Lightning connector due to its poorer quality- this is Apple’s own guide on the subject.)
Regrettably, just as you’ll find many fake Apple cables out there, you’ll also see ones with bogus “MFi Certified” claims on the box. Don’t believe everything you read!
Our Genuine MFi-Certified Cable versus a Rival’s Cheap Uncertified One
Inside the Genuine MFi Cable
We stock MFi-certified cables from a company called Sumvision. You can see from our disassembly photos that the connector of these contains a plastic shroud, in turn containing a metal compartment, in turn containing the connector board holding the genuine Apple ICs (including the two important ones described above).
Once the cover is off, we can see the metal compartment.
With the metal compartment removed, we can now see the MFi chips.
A closer view of the genuine Apple MFi ICs inside our Sumvision cable.
Apple’s old 30-pin “dock” connector had numerous pins that allowed data and power to flow independently. With Lightning, the connector has been reduced to just 8-pins and the E75 behaves as a negotiator.
How The Handshake Protects the Device
Once the cable is connected, the E75 informs the Tristar chip (on the iPhone or iPad itself) that it’s an official Apple or MFi cable, and wants to pass 5v charge to the battery. The Tristar requests and receives a password from the E75. This completes the handshake. (The E75 also provides security for the device, in that it only allows the peripheral access for what it needs; e.g. a speaker dock will not get full access to an iPad).
The other- even more important- IC is the NX20P3. This is a sophisticated “load switch” that features current limiting and filtering functionality including protection from overvoltage and reverse polarity. Any voltage issues, current surge, ripples or any other regulation discrepancies on the 5V charging line can quickly be switched to ground (i.e. away from the device itself).
This is really nice, because it stops your iPhone or iPad from getting fried!
Why They’re Required- and What Happens When Cheap Cables Leave Them Out
Take a look at the iPad Air Tristar (U6000) schematic. F6, PPVBUS_PROT- seen in red here- is the main 5V line coming from the charger. It’s clear that Tristar directly faces the outside voltage coming from the Lightning cable. If the NX20P3 is carrying out its intended function properly, then this will be filtered and clean.
On the other hand, if- as often happens with cheap cables- it doesn’t include anything like an NX20P3 and an imitation E75 gives the go-ahead anyway (effectively lying that the current is being filtered), the Tristar is directly vulnerable to any fluctuations or spikes in the current direct from the charger. This often results in serious damage sooner or later.
Near the bottom, we can see two (green) I2C data lines. These are effectively an “intercom” that communicates with the entire “house”, talking to the processor, backlight driver, and Chestnut IC. If they’ve been damaged by a power surge, the entire phone will fail to boot. This is one of the commonest symptoms of failure in the Tristar IC.
Note PMU_USB_BRICKID (blue, line C2). This line identifies which charger type is plugged in, e.g. whether it’s an iPhone or iPad charger, and whether it should pull 1 or 2 amps. If this line is damaged and the charger can’t be detected, you may well get “Accessory not supported”- another classic symptom of Tristar damage.
D6, OVP_SW_EN_L (magenta) is the overvoltage protection toggle- one of the most important lines- which goes direct to the Power Management IC (PMIC – U8100). From the U8100 schematic, we see that it, in turn, connects to the VBUS_OVP_OFF. This essentially lets the PMIC know to turn the overvoltage protection off.
So- in short- when you plug a Lightning cable in, the Tristar communicates with the E75 (genuine or otherwise) and then toggles on the overvoltage protection enable line. This tells the PMIC to turn off overvoltage protection since the charging current now being supplies is being safely filtered by the NX20P3.
Of course, on cheap or fake cables, this alleged filtering doesn’t actually take place and as soon as there’s a spike or ripple in the power from the charger, it can cause serious damage to the Tristar. This happens particularly often when using a fake cable with a car charger, due to power spikes associated with the vehicle starting.
Our Rival’s Cheap Non-MFi Cable- What’s (Not) Inside
So… having taken apart one of our own cables, we were interested to see what our nearby rivals were selling. We visited one store- which we won’t name- and noticed that their Lightning cables very obviously weren’t official.
It didn’t include MFi certification either, which is hardly surprising- having taken it apart, the difference is obvious- it very clearly doesn’t contain any of the genuine Apple chips ours does.
Technically, it might be argued that this isn’t a “fake” since it’s really trying to pass itself off as a genuine Apple product. However, you can certainly call it a cheap and nasty cable that’ll place your iPhone or iPad at serious risk of getting zapped due to the fact it completely lacks the protective circuitry of the genuine MFi one. It’ll charge your device, but sooner or later theres a good chance it’ll pass on a current spike or fluctuation and damage it.
Bear in mind that our MFi-certified cables don’t cost much more than the unofficial ones- around £4 difference in this case. However, it’s up to you to decide if it’s worth risking hundreds of pounds worth of damage to your iPhone or iPad to save less than a fiver on a cable. (Yes, you’ve probably guessed our opinion on this…!)
Symptoms of Tristar Chip Failure
The Tristar- or charging IC as it’s often known informally- does several things. The symptoms of failure can include:-
- Charger not being recognised
- Charger says “accessory not supported” (even if you go back to a known-good charger and cable).
- Phone claims that it’s charging but obviously isn’t doing so (fake charging)
- Simply doesn’t turn on at all
- Battery discharges much faster than expected
- Battery stops charging after reaching a certain percentage
- Phone switches off after battery drops below a certain point
- USB connection to computer is flakey
Versions and Codes Associated with Tristar IC
At the time of writing (mid-September 2017), there exist five different variants of the Tristar IC. Although often referred to as the “U2”, this isn’t strictly correct. U2 is merely a schematic code Apple use for some devices.
In many cases, the same IC (e.g. the 1608A1) is referred to by different codes on schematics for different models (e.g. it’s “U2” on the iPhone 5 schematic, but “U1300” and “U5900” on the iPad Mini 1 and iPad 4 respectively). And on the other hand, the same code (e.g. “U2”) can refer to more than one IC on different schematics (e.g. “U2” refers to the 1608A1 on the iPhone 5, but to the 1610A1 on the iPhone 5C and 5S schematic).
Regardless of all this, they’re generally referred to collectively as “Tristar”.
The complete list of Tristar ICs in order of date is as follows:-
| Chip name | Schematic code | |
| NXP 1608A1 |  |
U2 – iPhone 5 U5900 – iPad 4 U1300 – iPad Mini 1 |
| NXP 1610A1 |  |
U2 – iPhone 5C/5S U6100 – iPad Air U1300 – iPad Mini 2/3/4 |
| NXP 1610A2 |  |
U1700 – iPhone 6/6+ U3500 – iPad Air 2 |
| NXP 1610A3 |  |
U4500 – iPhone SE U4500 – iPhone 6S/6S+ |
| NXP 610A3B |  |
U4001 – iPhone 7/7+ |
Replacing the Charging IC
So how do we go about replacing a faulty Tristar? Once the problem has been diagnosed as a Tristar issue, we’ll take out the faulty Tristar from the logic board and replace it with a new one. On some devices this may require removing underfill.
While simple in principle, this is not an easy repair to carry out, and should only be done by an experienced technician. For example, if the board is overheated in the process of removing and fitting the IC, it can lead to other problems like CPU failure.
Fortunately, we’ve been carrying out iPhone and iPad repairs for a long time now, and have the experience needed to do this successfully- we’ve been in business for over fifteen years, and repairing iPhones almost since they first came out over ten years ago.
We’ll Fix It For You!
Whether you’re looking to have your own iPhone or iPad repaired, or whether you’re calling on behalf of another business looking to contract out one of the more problematic repair jobs, get in contact with us and we’ll arrange repair at a surprisingly affordable price.
Repair St Andrews was founded in 2011, so you know that we’re an established company that you can trust.
That’s why we’re known as one of East Scotland’s most trusted independent Apple iPhone and iPad repair centres. The good news is that we accept repairs via delivery services throughout the UK and most of Europe. Contact us online, by telephone or in person to arrange a repair.
